Spinnerette



United States Patent 3,044,155 SPINNERETIE Harold W. Robinson, Union, N.J., assignor, by mesne assignments, to Engelhard Industries, Inc, Newark, N.J., a corporation of Delaware No Drawing. Filed Aug. 2, 1957, ar. No. 675,826 6 Claims. (Cl. 29-1335) The present invention relates to spinnerettes for the production of synthetic fibres and, more specifically, to such spinnerettes made from noble metals.

In the production of synthetic fibres where the corrosion of the spinnerette by the chemical action of the spinning bath is an important factor, as is the case e.g. in the viscose process, spinnerettes made from noble metals are generally used. Alloys containing predominantly platinum or rhodium and gold alloys containing smaller amounts of platinum are the preferred material. However, these spinnerettes show an insufficient hardness and have to be replaced after a comparatively short lifetime because, under the pressures applied during the spinning process, the spinning orifices do not retain the exact shape and size required for the production of synthetic fibres. The faces of these spinnerettes are vulnerable to damage which, too, causes deformation of the orifices. Even alloys with a high content of costly platinum, which show a greater hardness than gold alloys, do not give satisfactory results.

In the attempt to obtain spinnerettes performing for a satisfactory period and especially those made from the softer but less expensive alloys as e.g. the alloy containing by weight 70 percent gold and 30 percent platinum,

it has been suggested to provide such spinnerettes with an electroplated coating of platinum. However, the slight increase of hardness obtained does not justify the increase of labor and expensive material involved. Further, in order to obtain a notable improvement in the hardness, it was necessary to deposit platinum coatings of a considerable thickness, e.g. up to 0.001 inch, but electrodeposits within this range are not smooth and even enough. Furthermore, the shape of the spinning holes and the contours of their edges become altered and rough, and at a limit of about 0.001 inch thickness of the paltinum coating,

3,044,155 Eatented July 17, 1962 In order to obtain the platinum coating, a solution of grams dinitrito-diamino platinum in 1 liter of water containing 20 grams di-amrnonium phosphate and 80 ml. ammonium hydroxide was used. The plating was eifected at the boiling point of the solution with a current density of 40 amperes per square foot. The electrolyte used for rhodium plating was a solution of 10 grams of rhodium sulfate and 75 ml. sulfuric acid in 1 liter of water, and the plating was effected at a temperature of 45 C. with a current density of 20 amperes per square foot; In the case of ruthenium, 10 grams of ruthenium nitrosyl chloride and ml. of sulfuric acid were dissolved in 1 liter of water, and the current density was 25 amperes per square foot.

The foregoing table shows that the increase of hardness obtained by electroplating with rhodium or ruthenium is superior to the increase due to plating with platinum.

I The thickness of the tested coatings was 0.001 inch, which the orifices reach a state of irregularity rendering the I spinnerette practically useless.

It has been found that the surface hardness of spinnerettes of the described composition can be greatly improved by coating the spinnerettes with ruthenium or rhodium. The deposits of those metals as obtained by electroplating upon spinnerettes made from noble metals, especially from alloys consisting mainly of gold or platinum, are substantially harder and therefore more resistant against mechanical stress than platinum coatings upon similar spinnerettes and of the same thickness. The following table illustrates the results of diamond point hardness tests made with two spinnerettes each, of two types of spinnerettes having been coated with platinum, rhodium and ruthenium to a thickness of 0.001 inch.

1 Theoretical hardness, assumed.

is above the limit found to be useful in'spinnerettes because of the resulting distortion of the shape and edges of the spinning orifices. However, by providing a coating not exceeding 0.00005 inch in thickness, the hardness increase obtained represents a great improvement over the unplated spinnerette when, in accordance with the pres ent invention, rhodium or ruthenium is applied, and best results were obtained with a coating of about 0.00002 inch. evidently, no reliable hardness tests can be made with such extremely thin coatings and only when actually performing for a long period are the spinnerettes proved to be superior. The coating with ruthenium and rhodium, when applied in a thickness not exceeding about 0.00005 inch, results in a substantial increase of the surface hardness of spinnerettes, thus contributing greatly to their lifetime but, at the same time, does not damage the shape of the spinning orifices because due to the specific hardness obtained, the thickness of the coating can be maintained extremely small.

It will be obvious to those skilled in the art that many modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.

What is claimed is:

1. A spinnerette made from an alloy comprising about percent by weight gold and 30 percent by weight platinum and coated by electroplating with a metal selected from the group consisting of rhodium and ruthenium.

2. A spinnerette made from an alloy comprising about percent by weight platinum and 10 percent by weight rhodium and coated by electroplating with a metal selected from the group consisting of rhodium and ruthenium.

3. A spinnerette according to claim 2, the thickness of the coating not exceeding about 0.00005 inch.

4. A spinnerette according to claim 2, the thickness of the coating being about 0.00002 inch.

5. A spinnerette according to claim 2, the thickness of the coating not exceeding about 0.00005 inch.

6. A spinnerette according to claim 2, the thickness of the coating being about 0.00002 inch.

References Cited in the file of this patent UNITED STATES PATENTS 1,990,277 Feussner Feb. 5, 1935 2,115,402 Spaanbrock Apr. 26, 1938 2,496,961 Schneider Feb. 7, 1950 r 2,539,096 Miller Jan. 23, 1951 2,600,175 Volterra June 10, 1952 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION July 17. 1962 Patent No, 3,044,155

Harold W. Robinson rtified that error appears in the above numbered petters Patent should read es It is hereby ce tion and that the said Let ant requiring correc corrected below for the claim reference lines 53 and 55,

Column 2,

h occurrence, rea

numeral "2, eac

ned and sealed this 27th day of November 1962,

Sig

(SEAL) Atteet:

ESTON G. JOHNSON XXEWXBEK DAVID L. LADD Commissioner of Patents Attesting Officer 

1. A SPINNERETT MADE FROM AN ALLOY COMPRISING ABOUT 70 PERCENT BY WEIGHT GOLD AND 30 PERCENT BY WEIGHT PLATIUM AND COATED BY ELECTROPLATING WITH A METAL SELECTED FROM THE GROUP CONSISTING OOF RHODIUM AND RUTHENIUM. 